I'm trying to design a Constant Current load for testing battery cells using the TLC070 Op Amp (what I happen to have on hand) and a low pass filtered (150Ohm + 470uF cap) PWM input from an Ardiuno. The OpAmp is driven by a 12v rail and the Arduino by 5v supply, all sharing a common ground.
The circuit is based off of this one:
The issue occurs if I set the input voltage to 0V, the Op amp will not drive the MOSFET (IRFZ44n) again. If the PWM is set to anything but 0, and the power to the OpAmp is turned on, the circuit works as advertised.
Is there a way to solve the issue turning on the CC Load from a 0 input PWM signal to a higher PWM signal?